Consciousness is the ability of an individual to detect any change occurring in his/her immediate external or internal environment even when he/she is not actively paying attention to it. 

For example, an individual could be conscious about a ball moving towards him/her and may hit him/her. 

While sensitivity is the unconscious response generated by an individual to the external stimulus they receive.  

For example, the individual after detecting the motion of the ball towards itself, either changes his/her position or gets hit by the ball and develops pain, indicates sensitivity.